Power query for power BI and excel

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BOOKS FOR PROFESSIONALS BY PROFESSIONALS®

Power Query for Power BI

and Excel

9 781430 266914

53999

ISBN 978-1-4302-6691-4

RELATED

Power Query for Power BI and Excel is a book for people who are tired of copying and pasting

data into Excel worksheets. Power Query, part of the Microsoft Power BI suite, is a tool that

automates the process of getting data into Excel and will save you hours of dull, repetitive,

and error-prone work. Power Query makes it easy to extract data from many different data

sources, filter that data, aggregate it, clean it and perform calculations on it, finally loading that

data into either your worksheet or directly into the new Excel 2013 Data Model used by Power

Pivot. This concise, practical book provides a complete guide to Power Query and how to use

it to solve all of your Excel data-loading problems.

Power Query for Power BI and Excel goes well beyond the surface of what Power

Query can do. The book goes deep into the underlying M language, showing you how to do

amazing things that aren’t going to be possible from just the GUI interface that is covered in

most other books. You’ll have full command of the GUI, and you’ll be able to drop into the M

language to go beyond what the GUI provides. The depth in this book makes it a must-have

item for anyone who is pushing Power BI and Excel to their limits in the pursuit of business

intelligence from data analysis.

• Teaches the basics of using Power Query to load data into Excel

• Helps you solve common, data-related problems with Power Query

• Shows how to write your own solutions in the powerful M language

For your convenience Apress has placed some of the front

matter material after the index. Please use the Bookmarks

and Contents at a Glance links to access them.

v

Contents at a Glance

About the Author ���������������������������������������������������������������������������������������������������������������� xv

About the Technical Reviewer ������������������������������������������������������������������������������������������ xvii

Acknowledgments������������������������������������������������������������������������������������������������������������� xix

Preface ������������������������������������������������������������������������������������������������������������������������������ xxi

■Chapter 1: Introducing Power Query ���������������������������������������������������������������������������������1

■Chapter 2: Power Query Data Sources�����������������������������������������������������������������������������17

■Chapter 3: Transforming Data with Power Query ������������������������������������������������������������63

■Chapter 4: Data Destinations�������������������������������������������������������������������������������������������99

■Chapter 5: Introduction to M �����������������������������������������������������������������������������������������115

■Chapter 6: Working with Multiple Queries���������������������������������������������������������������������149

■Chapter 7: Power Query and Power BI for Office 365����������������������������������������������������167

■Chapter 8: Power Query Recipes �����������������������������������������������������������������������������������189

Index���������������������������������������������������������������������������������������������������������������������������������243

1

Chapter 1

Introducing Power Query

This book is for people who spend a lot of time working with Excel building reports and dashboards. More specifically,

this book is for people who work with Excel building reports and dashboards and who are bored with copying and

pasting data into worksheets, bored with clicking the same sequence of buttons every month to clean and shape

that data, and bored with fixing the problems associated with complex formulas, dirty data, and the errors that are

inevitable when you have to follow the same procedures over and over and over again. The good news is that Power

Query is here to free you from these dull, repetitive tasks and give you time to concentrate on what’s important:

analyzing your data and gaining insights from it. Even better, Power Query is easy to use and lots of fun to learn

(so long as you’re the kind of person who thinks that playing with data can be fun—no need to feel ashamed if you do)

and, as a result, it will make you more efficient, more productive, and, hopefully, less bored.

Power Query and Power BI

Power Query is an Excel add-in developed by Microsoft, and its purpose is to make it easier to load data into Excel from

external data sources. It’s part of the Power BI suite of tools and, as such, it’s just one tool out of many that you can use

when developing what are called “self-service Business Intelligence solutions” in Excel. What is “self-service Business

Intelligence?” I hear you ask. Well, it’s just a fancy term for those reports and dashboards that you build as part of your

job. The aim of a Business Intelligence (usually shortened to “BI”) solution is to make business information accessible

to people so that they can use it to make informed decisions about how to do their job; other terms you may have

heard include “management information systems” and “decision support systems”. The whole process is referred to

as “self-service” because the people who want to use this data, the analysts, the accountants, the managers and so on,

are also the people who are building the reports—they do not have to rely on help from the IT department to do so.

Of course, this has always been one of the most popular uses for Excel but, with Power BI, Microsoft has focused on

making it even easier to do this. By doing so, Microsoft has reaffirmed Excel’s position as the tool of choice for anyone

who works with data as part of their job.

Given that Power Query is just one part of the Power BI suite, it’s important to look at all of the components of

Power BI so you can put Power Query in context, understand what it does, understand when you should use it

and when another tool is more appropriate.

Power BI Components

The components of Power BI divide up into two groups: Excel add-ins and the cloud services that are available via

Power BI for Office 365. Following are the Excel add-ins:

• Power Query

• Power Pivot

• Power View

• Power Map

Chapter 1 ■ Introducing Power Query

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And following are the cloud services available via Power BI for Office 365:

• Power BI Sites

• Q&A

• Power BI Data Catalog

• Mobile BI app

Now, let’s look at each one of them in a bit more detail, in the order that you are likely to use them, so that you

can see what their roles are.

Power Query

Conveniently enough for this book, Power Query is going to be the first component in the Power BI suite that you use

when building a new BI solution. That’s because the first step in creating any kind of report or dashboard is to get hold

of the source data for it. Power Query allows you to connect to a wide variety of different data sources, extract data

from them quickly and easily, and define a series of repeatable steps to clean, filter, and otherwise transform your

data before it gets loaded into Excel. Power Query gives you the option of loading data directly into the worksheet or,

if you are using Excel 2013, into the new Excel Data Model. Obviously, this is a greatly simplified account of what

Power Query is capable of, and the rest of the book will go into a lot more detail!

Power Pivot and the Excel 2013 Data Model

The Excel Data Model is an in-memory database engine that runs inside Excel and that allows you to load very large

amounts of data (much larger than you could ever fit on a single worksheet—it can handle millions, even tens of

millions of rows of data) for analysis purposes. In a traditional Excel BI solution, you might be used to loading your

raw data onto a hidden worksheet and then using VLOOKUPs to move values from this hidden worksheet into a

report, or using PivotTables to slice and dice your data. The Excel Data Model gives you a better way of doing both of

these things. If you load your data into the Excel Data Model, you no longer have to use a hidden worksheet to store

your data; once the data is in the Excel Data Model, you can create PivotTables directly from it and you can use Excel’s

Cube Formulas to import individual values into cells in the worksheet.

The Excel Data Model is, in fact, the database engine behind the Power Pivot add-in, first released for Excel 2010.

In Excel 2010, Power Pivot was a self-contained unit: the add-in consisted of a user interface as well as a database

engine. In Excel 2013, it was split in two and the database engine was built directly into Excel. The Power Pivot add-in

still remains but only as a user interface. You have to use the Power Pivot add-in to be able to use certain, more advanced

functionality, but you do not need it if you only want to perform basic tasks. The split between Power Pivot and the Excel

Data Model in Excel 2013 has confused many people and, as a result, you will find plenty of books and articles that still

refer to both as Power Pivot.

Apart from the ability to work with very large data volumes, loading data into the Excel Data Model has many

other advantages over the “hidden sheet” method including the following:

• Multiple tables of data can be loaded into it. After you’ve loaded the tables of data, you can

create relationships between those tables similar to those that you can create in Access or other

relational databases. Once relationships have been created, you can create PivotTables that

include data from all of these tables—traditional PivotTables are limited to just one source table.

• Complex calculations can be written in DAX, the language of Power Pivot. These include time

series calculations, percentage shares, and many other types of calculations that are difficult to

implement in regular Excel formulas.

Chapter 1 ■ Introducing Power Query

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• The Excel Data Model compresses data very efficiently so loading your data into it, instead

of into the worksheet, can drastically reduce the size of your workbooks. This is particularly

important if you intend to upload your workbook to a Power BI site because there are limits on

the size of workbooks that can be uploaded, as you’ll soon find out.

• You can add features such as hierarchies, which allow your users to drill down through your

data following a predefined path, and KPIs, which are special calculations that help users track

business performance.

Power Pivot and the Excel Data Model are together a gigantic topic and deserve a book to themselves; indeed

many excellent books, white papers, and blog posts are already out there. If you are serious about building BI

solutions in Excel, then you owe it to yourself to learn more about this topic.

Power View

Power View is a new feature of Excel 2013 that allows you to create attractive, interactive dashboards as new

worksheets inside your workbook. It is very closely related to, but not to be confused with, a stand-alone application

that is also called Power View but that is only available in SharePoint. Power View in Excel takes data stored in a

worksheet or from the Excel Data Model as its starting point, and then, using drag and drop, it allows you to create

tables, charts, and maps that can be easily filtered and sliced. Even if you can already build dashboards and reports in

a regular worksheet with PivotTables or PivotCharts, Power View gives you more options for visualizing your data,

it is easy to use, and the end product is more visually appealing.

Power Map

Power Map is an Excel add-in that allows you to overlay geographic data onto 3-D maps. For example, if you work with

retail data, you can use Power Map to plot sales of all of your stores on a map. At the location of each store, you can

use it to show a bar graph of sales within that store. Once you’ve done this, you can explore these maps, panning and

zooming in, and even record “tours” that show data for many different locations. Like Power View, its main strength is

its “wow” factor—swooping low over a city and seeing hundreds of tiny graphs appear over a neighborhood you know

makes for a very impressive spectacle.

SharePoint and Power BI for Office 365

Having loaded your data into Excel using Power Query, created PivotTables and reports using Power Pivot and the

Excel Data Model, and created dashboards and visualizations using Power View and Power Map, the next thing

you are likely to want to do is share the fruits of your labor with your colleagues. There’s nothing stopping you from

e-mailing your workbook to them, but there is a better way: SharePoint.

The on-premises version of SharePoint is used by many organizations to manage documents. SharePoint

Enterprise Edition includes Excel Services, which allows Excel workbooks to be viewed and edited in a browser. Excel

Services does not support all Excel desktop functionality, but it does have very good support for Excel’s BI features:

PivotTables, Excel Cube Formulas, and Power View sheets can all be viewed in a browser. This makes SharePoint and

Excel Services a great way to make your reports available to your coworkers.

An increasing number of organizations are now moving to SharePoint Online, Microsoft’s cloud-hosted

version of SharePoint, which is available as part of Office 365. If your organization has moved to Office 365 and uses

SharePoint Online, you can publish your workbooks to a SharePoint Online document library, share them with other

people, and interact with them in a browser via Excel Services. For simple scenarios, this may be sufficient for your

reports and dashboards.

Chapter 1 ■ Introducing Power Query

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If you purchase an additional Power BI for Office 365 subscription, you get several very useful features in addition

to what is available with a regular Office 365 subscription:

• While SharePoint Online allows you to upload documents of up to 2GB in size, if you want

to be able to view your BI workbooks using Excel Services in a browser, you are limited

to workbooks of only 10MB. Power BI for Office 365 allows you to increase this limit by

distinguishing between the size of the data in the Excel Data Model (which can be anything up

to 250MB at the time of writing) and the rest of the workbook (which is still limited to 10MB).

• Data held in the Excel Data Model of workbooks can be refreshed on a schedule, even if

the data sources are not themselves in the cloud. Installing the Data Management Gateway

component on-premises allows Power BI for Office 365 to connect your workbook in the cloud

with your organization’s SQL Server and Oracle databases.

• The Power BI Data Catalog allows administrators to provide access to a variety of public and

corporate data sources through a Power BI site by exposing them as OData data feeds.

• Power Query users can also share their work with their colleagues via the Power BI Data

Catalog. (This will be explained in more detail in Chapter 7.)

• Power BI sites provide a smarter, more businesslike way to organize your reports and

dashboards than a regular SharePoint Online document library.

• Power BI sites also provide management dashboards that allow you to track which workbooks

your colleagues have been using and when.

• Q&A is a feature of Power BI for Office 365 that allows users to query the data held in the Excel

Data Model of workbooks using English language queries and then see the results of these

queries displayed in a Power View report. While Q&A only speaks English at the moment,

other languages may be supported in the future.

Mobile BI

The final component of the Power BI suite is the Mobile BI app. If you have uploaded a workbook to a Power BI

site, you have the ability to see parts of it—tables, charts, named ranges, PivotTables, PivotCharts, and Power View

dashboards—via the Mobile BI app. This is a Windows 8.1 app designed to allow users of Windows tablets to access

BI data while they are away from their desktops. Similar apps for other mobile platforms such as iOS will be released

in the future.

Workflow Summary

In summary, then, the Power BI workflow is:

1. load data from external data sources into Excel using Power Query

2. model data in the Excel Data Model and add calculations using Power Pivot

3. build reports and dashboards on this data using PivotTables, Excel Cube Formulas,

Power View, and Power Map

4. publish your workbook to a Power BI site in SharePoint Online so other users can access

the reports in it

Figure 1-1 shows the workflow in more detail.

Chapter 1 ■ Introducing Power Query

5

Power Query and Power BI Licensing

The licensing model for Power Query and Power BI for Office 365 is not straightforward and requires some

explanation. For Excel 2013 users, Power Query is licensed in exactly the same way as Power Pivot and Power View

(though not Power Map, which is only available if you have an Office 365 subscription), and it is available as for free if

you have bought one of the following:

• the stand-alone version of Excel 2013

• an Office 2013 Professional Plus license for your desktop

• an Office 365 subscription that gives you access to the Office 2013 Professional Plus desktop

tools. There are a large number of subscription SKUs, but the Office 365 ProPlus, E3, and

E4 SKUs all include the right version of Excel.

Text File

Database

Database

Power Query

PivotTables/Excel

Cube Formulas

Power View

Reports

Power Map

Workbook Creator

Excel Data

Model/Power

Pivot

Worksheet

Data Refresh

Mobile Bl

Power View

Reports

PivotTable Reports

SharePoint Online

Other Users

Q&A

Excel

Data Storage Reports

Excel Services

Publish

Power Bl Site

Figure 1-1. The Power BI workflow

Chapter 1 ■ Introducing Power Query

6

If you have Excel 2010, the only edition that supports Power Query is Office Professional Plus Service Pack 1.

Power View and Power Map are not available for Excel 2010, but Power Pivot is available for all SKUs of Excel 2010.

The ability to view Excel workbooks stored in the on-premises version of SharePoint in a web browser is only

available in SharePoint Enterprise Edition, and the functionality works best if you have SharePoint 2013. In addition,

you will need to have Power Pivot for SharePoint installed.

The cloud-based services included in Power BI for Office 365 (Power BI Sites, Q&A, the Power BI Data Catalog,

and the Mobile BI app), are covered by a separate subscription model. A prerequisite of using these services is an

Office 365 subscription that includes SharePoint Online; you then need to purchase an extra subscription to use the

services themselves.

Full licensing details, as well as links to install the various Power BI components, can be found at

http://www.microsoft.com/powerbi. None of the Power BI Excel add-ins are available in the Apple Mac or

Windows RT versions of Excel.

Installing Power Query

Power Query must be downloaded and installed separately after Excel has been installed; if you do not see the Power

Query tab in the ribbon after you have installed it, you may need to enable the add-in manually. It requires Windows

Vista or greater, if you are installing it on a desktop PC, or Windows 2008 or greater if you are installing it on a server.

It also requires .NET 3.5 Service Pack 1 and Internet Explorer 9 or greater.

There are 32-bit and 64-bit versions of Power Query available. If you have the 32-bit version of Excel installed,

you must install the 32-bit version of Power Query; if you have the 64-bit version of Excel, you must install the 64-bit

version of Power Query. The 64-bit version is recommended if you are going to be working with large amounts of data.

New versions of Power Query are released on a regular basis and these can include significant new functionality.

The Update version on the Power Query tab in Excel will light up when a new version is available to download.

Power Query Concepts

Now that you have seen where Power Query fits in the Power BI suite, it’s time to start looking at it in more detail.

A good place to start is by defining some of the concepts and terminology you’ll encounter when working with Power

Query. Luckily, there isn’t much terminology to define. (If you find it easier to learn by seeing rather than reading, you

may prefer to skim over this section and then move onto the next one, where you’ll find the same concepts described

by means of a worked example.)

The most important concept in Power Query is that of a query. (Unfortunately, this means you have to talk about

“Power Query queries.”) A query is a job that imports data from one or more data sources, optionally does something

to the data such as filter it or aggregate it, and then loads it into Excel. Queries are stored inside an Excel workbook,

and one workbook can contain multiple queries. Queries themselves can be used as data sources for other queries;

two queries may also be merged together rather like one table can be joined to another in SQL, and a query can be

appended onto the end of another.

A query is composed of one or more steps that are arranged in a specific order. A step may connect to a data

source to retrieve data (usually the first step in a query does this, but subsequent steps may do this, too), or it may take

the data returned by a preceding step and apply some kind of transformation to it. The last step in a query returns the

output of the query as a whole. Steps are defined in Power Query’s own expression language, “M,” which sadly bears

no resemblance to Excel formula language or VBA and is, in fact, a functional language like F#. When you create a new

step in the Power Query user interface, Power Query will generate the M code necessary for that step automatically.

If you are a confident programmer, you can edit the code behind each step yourself or create new steps by writing your

own M code. However, in the majority of cases, this is not necessary.

Although Power Query steps may connect to external data sources, there is no concept of a connection to a data

source as a separate object, and Power Query cannot use connections defined elsewhere in Excel (that’s to say, the

connections that can be found on the Data tab in the ribbon). However, the output of a Power Query query does

become a traditional Excel connection and can be used just like any other connection. This allows Power Query to be

able to output results to a table in a worksheet, for example.

Chapter 1 ■ Introducing Power Query

7

Power Query Walkthrough

This section illustrates the concepts described above by walking through the creation and editing of a simple Power

Query query. It also acts as a brief guided tour of the Power Query user interface. As you start to use Power Query, you’ll

find that all kinds of extra menus, panes, and tabs appear depending on what you’re doing. In the following chapters,

as you learn more about Power Query functionality, you’ll become more familiar with the details of the user interface.

Creating a Simple Query

The starting point for all of your Power Query work will be the Power Query tab on Excel’s ribbon menu, shown in

Figure 1-2.

Figure 1-2. The Power Query tab

On the left-hand side of the Power Query tab, in the Get External Data section, you can see the options to import

data from different types of data sources, while in the Excel Data section you can see a button to import data from an

Excel table in the current workbook. Elsewhere in the Power Query tab, you can see options for combining data from

different queries as well as various other administrative options that will be covered later in this book.

Click the From File button. On the drop-down menu click on the From CSV option as shown in Figure 1-3.

Figure 1-3. The From CSV button

Chapter 1 ■ Introducing Power Query

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A dialog box will appear. You should select the file 01_01_SimpleSales.csv from the sample files for this chapter.

When you do this, the Power Query Query Editor window will appear as shown in Figure 1-4. The five main areas of

the Query Editor window, marked in Figure 1-4, are the following:

1. The Query Editor toolbar. This is a ribbon menu containing all of the options for creating

new steps in your query.

2. The Formula Bar. This is where you can edit the M expression for each step in the query.

3. The Navigator pane. This collapsible pane allows you to navigate through certain types of

data sources such as XML files so you can find the particular data you are looking for.

4. The Results pane. This is where you can see the data returned by the currently

selected step.

5. The Query Settings pane. This pane displays the name of the query you are editing, a

description, a list of all of the steps in the query in the Applied Steps section, and two check

boxes that control where the output of your query will be sent to in the Load Settings section.

Figure 1-4. The Query Editor window

Chapter 1 ■ Introducing Power Query

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At this point, a new query will have been created, called Query1, which has three steps already created for you

that are listed in the Applied Steps section on the right-hand side of the screen in the Query Settings pane. The output

of the third step, called ChangedType, will be visible in the Results Pane. If you click any of the other earlier steps, you

will see the output of the query after that step has been executed there instead. (This makes it easy to debug a Power

Query query because it allows you to see how each step changes the data.)

Now click the Apply & Close button in the top left-hand corner of the editor and the window will close. Since the

Load to Worksheet check box (found under Load Settings in the bottom right-hand corner of the screen) was checked,

a new worksheet will be created and the output of this query will be shown in a new Excel table located at cell A1 of

the new worksheet, as shown in Figure 1-5.

Figure 1-5. Query output

Congratulations! You have created your first Power Query query.

Editing an Existing Query

Queries can be edited after they have been created. Before you can do this, though, you need to go back to the Power

Query tab on the ribbon and click the Workbook button in the Manage Queries section, so you can see a list of all the

queries present in this workbook. When you do this, the Workbook Queries pane will appear on the right-hand side of

the screen, as shown in Figure 1-6. The query you have just created, Query1, will be visible in this pane.

Chapter 1 ■ Introducing Power Query

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Now, move your mouse cursor over the Workbook Queries pane and Query1. When you do this, a fly-out box

will appear showing a preview of the data, when the query was last refreshed, and where the query is to be loaded .

Also on the fly-out box is a series of clickable menu options plus ellipses that, when clicked, reveal even more

menu options. (See Figure 1-7.) The menu options in this fly-out box are also available in a drop-down menu if you

right-click the query in the Workbook Queries pane.

Figure 1-6. The Workbook Queries pane

Chapter 1 ■ Introducing Power Query

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Click the Edit option on the fly-out box and the Query Editor window will reopen, looking just as it does in

Figure 1-4. Next, click the Remove Rows drop-down menu, which can be found in the center left of the Home tab of

the Query Editor toolbar in the Reduce section, and click Keep Top Rows. This will add a new step onto the end of

your query that filters out all but a given number of rows at the top of your query. Before it can do this, though, you

will need to tell Power Query how many rows you want to keep. When you click the button, Power Query will open a

dialog box, as shown in Figure 1-8, asking you for the number of rows to keep. Enter the value 2 to keep only the top

two rows and click OK.

Figure 1-7. The Workbook Queries fly-out menu

Chapter 1 ■ Introducing Power Query

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Once you have clicked OK, you will see the data has changed. Before, there were three months listed—January,

February and March. Now, there are only two—January and February, as shown in Figure 1-9. A new step has also

been added to the query called KeptFirstRows and the M code for this step is visible in the formula bar.

Figure 1-8. The Keep Top Rows dialog box

Figure 1-9. The output of the KeptFirstRows step

Finally, click the Apply & Close button, and you will see the new output of the query appear in the Excel table in

the worksheet, as shown in Figure 1-10.